1. Field of the Invention
The present invention is directed to the preparation of acyl alkylisethionate ester salts, intermediates thereof, and the application of the same in consumer products.
2. Background of the Related Art
Acyl alkylisethionate esters are anionic surfactants that may be used in a variety of personal care cleansers such as soaps, cosmetic compositions, and cleaning formulations. One acyl isethionate ester, sodium cocoyl isethionate (“SCI”), is an ester currently used extensively in soap-combi bars (i.e., syndet bars) due to its low solubility in water and mildness on the skin, as compared to harsher fatty acid soap bars.
U.S. Pat. No. 5,384,421 to Day et al. discloses a method for making salts of acyl isethionates using a direct esterification of a fatty acid with one or more salts of a selected hydroxyalkanesulfonic acid in the presence of a catalyst selected from the group described therein.
U.S. Pat. No. 6,069,262 to Walele et al. discloses a composition of matter of fatty acids of hydroxylalkyl sulfonate salts, in particular sodium cocoyl isethionate (SCI) and process for preparing the same.
Due mainly to its low water solubility, SCI is not suitable for use in liquid cleansers. One method for improving SCI's limited water solubility is to combine SCI with other surfactants such as taurate, amphoacetates and betaines. This combination of surfactants, however, produces relatively hazy solution, which tend to separate during storage.
Therefore, it would be desirable to produce acyl isethionate esters that are highly water soluble, hydrolytically-stable and non-irritating for use in aqueous as well as non-aqueous consumer products such as personal care cleansers.